I want a Wankel Engine

I don’t know why but the idea of an engine without pistons seems like a lot of fun. Does anyone around here know anything about Wankel engines? Could I possibly get one to put on a motorcycle?


All about Wankel Engines.

I don’t think you can get one for your motorcycle. While they’re cool, they aren’t very efficient and generally don’t meet emission standards.

Just buy a Mazda RX-8, I believe it’s the only production car out now with a rotary engine.

And also tend to get worn out pretty quickly.

Get a used third-generation RX-7. It’ll cost you an arm and a leg, but the payoff will be worth it.


I thought a Wankel Engine might have been a cute term for a Vibrator.

I’ll make my exit from this thread…


Wow, they’re LESS efficient? Why even invent the thing?

Because they’re cool?

Well, they do have one thing going for them - they sure rev like the bejesus. Sadly, torque isn’t their big suit - nor is fuel consumption.

Umm … no. If oil changes are attended to regularly (like every 3k miles) and they’re not overheated, modern rotaries are as reliable as any piston engine. It is not unheard of for them to exceed 200K miles. A friend of mine once had an RX-7 with over 200K miles on the clock and he tortured the hell out of that thing just to see how much abuse it could take. He finally just replaced the engine with a fresh one just for the hell of it because he got tired of not being able to break it.

Fuel mileage does indeed suck, but the RX-8 is supposed to be the best yet. But, as Boo Boo Foo pointed out, they rev like crazy … 8000 RPM is a breeze, and I think the RX-8 will take even 9500 in stride. And they sound so different from any other engine. Un-muffled they are LOUD. Wankels have one of the best horsepower-to-displacement ratios of any engine. Note that the third-generation RX-7 and the RX-8 produce something over 250hp in stock trim with only 1.3L displacement … keep in mind the average stock V8 takes 5.0L displacement to achieve that.

There have been a couple of motorcycles produced with Wankels over the years, but I’m not aware of anything current. http://www.monito.com/wankel/norton.html

I just checked Cycle Trader and found 23 Nortons for sale, but no RCEs. The newest bikes listed were 1975 models.

Small rotary engines are exceedingly rare. A Mazda engine would be too large for any reasonable cycle application.

As a kid I made a working model of one from a kit. Might be a low cost alternative for you.

I’m curious as to why the fuel consumption sucks. It would seem like a Wankel engines have a better chance at conservation of energy-- the gas pushes the rotor in the same direction that it’s already moving, right? Piston engines have to push down pistons moving upwards in order to raise their counterparts, and so on, right? Therefore you think you’d lose a bit less energy with a Wankel system than a piston system. Is it just not enough of a gain? Does it have to do with the way the fuel/air ratio works in a Wankel engine? The way the mixture is sparked?

I guess the short question is how the physics of Wankel engines work vs. piston engines.

Suzuki made the RE5 with a Wankel rotory engine for a couple years in the mid 70’s. I had one, for a while. One of the ugliest, heaviest motorcycles I have ever seen, and for sure that I have owned.

Good as a novelty or conversation piece, but as a regular rider, I can’t reccomend it.

Bought mine locally, sold it on ebay for a tidy profit. Still have some parts, including the “Buck Rogers” exhaust system.

How is Rap like Porn? Both are better with the sound turned off.

This site has an animation explaining how the Wankel works.

I know they’re not really the most practical things in the world but I thought it’d be nice to have one around as a project.


IANA Wankel engineer, but I think it is precisely that motion of the rotor and the elongated combustion chamber that makes them so inefficient. They apparently don’t burn evenly across the rotor face, hence the dual ignition setup on most Mazdas. They have a leading and a trailing spark plug in each rotor housing. One basically ignites the mixture while the other “cleans up” by firing a split second after the first to ignite any unburnt mixture. If everything isn’t burning totally efficiently, you’re throwing unspent fuel into the exhaust. That’s fuel that could have been used for power. With Mazda’s revamping of the rotors and housings in the RX-8, they have supposedly improved fuel economy by quite a bit and increased power. They are now supposedly producing the same power in a naturally aspirated rotary as the last RX-7 which was turbo-charged. Pretty impressive.

I think that bike’s just quirky-looking enough to be cool, gatopescado. Eye of the beholder I guess. Here’s a great link.


Yeah, it was “quirky-cool”, like all my bikes (RZ350, GB500, GT360, WR650), but look closely at the specs on that very good site you linked:

522 pounds!! :eek: :rolleyes:

What a pig!

I also got rid of it because spark plugs were difficlult to find and expensive when you did, like $25 per plug! And it was ugly. And did I mention heavy? :wink:

I should have hung on to it. I was hoping it would increase in value dramaticly. Dramaticly was pretty optimistic.

Never kiss an animal that can lick it’s own butt.

yeah, I saw that weight. YIKES!

Alas unless someone decides to produce small rotary engines or I make friends with a machinist I’ll probably never own one. <sigh> Even for a little hobby bike I don’t think I’d ever be able to afford to maintain it properly.